Field of the invention. The present invention relates to a knob arrangement for operating parking brakes intended for use in vehicles comprising brake units such as drum brakes or disc brakes on two opposing wheels in a pair of wheels, and an electrically operated tightening means for applying or releasing braking force to said brake units.
Background Information. A large number of suggestions for electrically maneuvered parking brakes for replacing conventional hand controlled parking brakes are known in the art. For instance, electrically maneuvered hand brakes are described in GB 2304838 A, WO/9221542 and EP 0398546 A2.
The purpose of the present invention is to achieve an electrically operated parking brake offering a number of advantages compared to previously known designs. According to the invention this is achieved primarily by a means, suitably a rotary potentiometer, being arranged to sense the knob""s position and send control signals to a first electric motor. The electric motor drives a tightening means, or tightener, for generating a braking force corresponding to the position of the knob. The knob is manually adjustable, and in its fully tightened position, at maximal braking force, capable of being locked mechanically. A control motor is arranged to automatically maneuver the knob to its fully tightened and locked position in response to incoming control signals. In its fully tightened and locked position, it is possible to release the knob from its locked position only through manual operation.
The present invention has several advantages, including the following. A great advantage of the knob as a maneuvering means in an electrical hand braking concept is its size. Because it is small in comparison to a traditional lever, it can be placed, for instance, in the middle console of the instrument panel thereby freeing room between the front seats of the car. Another advantage is that the control consists of few parts meaning that production costs can be kept low.
The maneuver force needed for the knob is significantly lower than is the case for conventional hand brakes. This means that a weak person will have no problem releasing an activated parking brake.
The risk of forgetting to set the hand brake on leaving the car is eliminated through an automatic application function on the knob control.
Because it is easy to design the knob/knob control as an independent unit that fits as a module in different car models, the number of variations of maneuvering units for different car models is reduced.
In static application, the function that entails moving the control axially and returning it a number of degrees increases child safety.
The knob functions well in dynamic braking because it is easy to maneuver.